Stator winding arrangement with connections for adjacent diamond coils

The present disclosure relates to the field of electric machines, and more particularly, stator winding arrangements.

Winding arrangements for stators are known, including winding arrangements with diamond-shaped coils. Electric machines that include such winding arrangements are particularly suited for certain applications, but improvements to such electric machines would be advantageous. For example, certain winding arrangements with coils positioned in adjacent slots require a many long connections between the poles of the winding arrangement. Accordingly, it would be advantageous to provide a winding arrangement with coils positioned in adjacent slots, but with and a limited/reduced number of long series connections between poles. Additionally, it would be advantageous to limit the number of welds required for the diamond coil winding arrangement and/or make the welds easy to complete. It would be of additional advantage to provide a balanced winding and/or a winding with a high slots per pole per phase count and multiple parallel paths per phase.

In at least one embodiment, a stator for an electric machine defines a plurality of poles. The electric machine includes a core including a plurality of slots and a multi-phase winding arrangement formed of a plurality of diamond coils is positioned on the core. Each phase of the winding arrangement comprise at least three parallel paths. At least one of the parallel paths includes a plurality of coils arranged on the core, and each coil is defined by coil legs and end turns. The coil legs include left legs and right legs extending through the slots of the core and arranged in layers within the slots. The left legs and right legs of each coil are connected by first end turns at one end of the core and second end turns at an opposite end of the core. The plurality of coils of the one parallel path includes a first pair of adjacent coils connected in series and a second pair of adjacent coils connected in series, the first pair of adjacent coils and the second pair of adjacent coils associated with four poles of the electric machine. Additionally, an extended coil connection connects the first pair of adjacent coils and the second pair of adjacent coils in series. An entry lead is provided at one end of the parallel path and an exit lead is provided at the opposite end of the parallel path. At least two poles which are not associated with the parallel path, exist between the entry lead and the exit lead

In at least one embodiment, a stator for an electric machine comprises a core including a plurality of slots and a multi-phase winding arrangement positioned on the core. Each phase of the winding arrangement comprises four parallel paths, each parallel path including at least a first pair of adjacent coils connected in series, a second pair of adjacent coils connected in series, and an extended connection connecting the first pair of adjacent coils and the second pair of adjacent coils in series. The first pair of adjacent coils are separated on the core from the second set of adjacent coils. The coils forming the first pair of adjacent coils and the second pair of adjacent coils are diamond shaped coil. Each of the four parallel path includes an entry lead and an exit lead, wherein the entry leads and the exit leads of all four parallel paths of each phase are arranged along an arc that spans at least 240 degrees around the core.

In at least one embodiment, a stator for an electric machine includes a core comprising a plurality of slots and a multi-phase winding arrangement positioned on the core. Each phase of the winding arrangement comprises a plurality of parallel paths. Each of the parallel paths is comprised of a plurality of adjacent coils connected in series. Each phase of the winding arrangement is associated with a plurality of poles and each pole is associated with a pole slot set including at least a leftmost slot, a middle slot, and a rightmost slot. For each pole slot set, (i) coil legs of a first parallel path are positioned in a first half of the layers of the leftmost slot and in the first half of the layers of the middle slot, and (ii) coil legs of a second parallel path are positioned in a second half of the layers of the middle slot and the second half of the layers of the rightmost slot.

The above described features and advantages, as well as others, will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and accompanying drawings. While it would be desirable to provide an electric machine that provides one or more of these or other advantageous features as may be apparent to those reviewing this disclosure, the teachings disclosed herein extend to those embodiments which fall within the scope of the appended claims, regardless of whether they include or accomplish one or more of the advantages or features mentioned herein.

A stator for an electric machine is disclosed herein. With general reference to, opposite sides of the statorare shown. The statorincludes a stator corewith a multi-phase winding arrangementpositioned on the stator core. Each phase of the winding arrangementincludes a plurality of parallel-connected paths(which may also be referred to herein as simply “parallel paths” or “paths”). The parallel paths are housed in groups of adjacent slots, wherein each group of adjacent slots and the associated conductors through such slots define one of a plurality of poles for the electric machine. As best shown in, each parallel path includes a plurality of coilspositioned on the core, and each coil is defined by in-slot conductors, end turnsthat extend between the in-slot conductors, and coil leads. Each pathincludes at least a first pair of adjacent coilsconnected in series and a second pair of adjacent coilsconnected in series. The first pair of adjacent coilsand the second pair of adjacent coilsare connected in series but are separated on the core such that they are not adjacent. Extended coil connectionsprovide the series connections between non-adjacent coils within the same path. The coil leadsand the extended coil connectionsare all located on a first end(i.e., the “lead end”) of the stator core.

Stator Core

shows a view of the stator corein isolation from the winding arrangement. The stator coreis comprised of a ferromagnetic material and is typically formed from a plurality of steel sheets that are stamped and stacked upon one another to form a lamination stack, but also can be formed of any low-loss material such as SMC (Soft Magnetic Core). The stator coreis generally cylindrical in shape as defined by a center axis, and includes an inner perimeter surface and an outer perimeter surface. The inner perimeter surface defines an inner diameter (ID) for the stator. The outer perimeter surface defines an outer diameter (OD) for the stator.

A plurality of teethare formed on the interior of the stator coreand directed inwardly toward the center axis. Each toothextends radially inward and terminates at the inner perimeter surface. Axial slotsare formed in the stator corebetween the teeth. Each slotis defined between two adjacent teeth, such that two adjacent teeth form two opposing radial walls for one slot. The teethand slotsall extend from a first endto a second endof the core.

The slotsmay be open or semi-closed along the inner perimeter surface of the stator core. When the slotsare semi-closed, each slothas a width that is smaller at the inner perimeter surface than at more radially outward positions (i.e., slot positions closer to the outer perimeter surface). When the slots are open, conductors may be inserted into the slots from the ID. In addition to the radial openings to the slotsthrough the inner perimeter surface (i.e., for open and semi-closed slots), axial openings to the slotsare also provided the opposite ends,of the stator core.

As shown in, the stator coreis configured to retain the winding arrangementwithin the slotsof the stator core. The winding arrangementis formed from a plurality of interconnected coils that are retained within the slots. The coils are comprised of multiple segments of insulated copper or other electrically conductive material that form loops. The loops generally extend through the slots and wrap around the teeth of the core.

Coils of Winding Arrangement

With reference now to, one of the coilsof the winding arrangementis shown in isolation from the winding arrangement. As shown in, each coil is a diamond-shaped coil that includes a plurality of straight in-slot conductors, a plurality of end turns, and a plurality of coil leads. The straight in-slot conductors(which may also be referred to herein as “in-slot segments,” “in-slot conductors” or “legs”) extend through the slotsfrom one end of the coreto the opposite end of the core. Two groupsandof in-slot segmentsare associated with each coil. Each group,of in-slot segmentsextends through a different slot of the core. Multiple in-slot segments are included in each group,. In the embodiment of, each group,includes four in-slot segments. These four in-slot segments are arranged in single file within the slots(i.e., in “layers” of conductors within the slot). Each slot is configured to retain some number of in-slot segments in layers of the slot. In at least one embodiment, the slotsare configured to retain twice the number of in-slot segmentsas the number of conductors of each group,(e.g., each group,includes four in-slot conductors, and each slot is configured with a total of eight layers of in-slot conductors).

In addition to the in-slot segments, each coilfurther includes end turnsand coil leads. The end turnsand coil leadsare provided as part of winding headsandof the winding arrangement, and are therefore arranged axially beyond the respective ends,of the stator core. As shown in, the end turns(which may be also referred to herein as “end loops”) extend between the two groups/sets,of in-slot segments. In other words, each end turnprovides a bridge from the end of a conductor in one groupto the end of a conductor in another group. Each end turnincludes a first angled portion(which may also be referred to herein as a “first segment”) and a second angled portion(which may also be referred to herein as a “second segment”). The first segmentextends along a first end turn direction that is angled relative to the axial direction (i.e., angled relative to center axis). Similarly, the second segmentextends along a second end turn direction that is angled relative to the axial direction. The two segments,meet at a vertexof the end turn. The vertexdefines the portion of the end turn where the coilchanges direction as it loops around the core (e.g., changing from a direction moving axially away from the core back to a direction moving axially toward to core). As shown in, the vertexmay be semi-circular shaped and may alternatively be referred to as a “U-turn” portion. As shown in, the angled portions,of the coiland the associated verticesresult in a coil with a diamond-like shape.

Similar to the in-slot segments, the end turnsare also comprised of a conductive material, such as copper. The diamond shape of the coilsmay be formed by providing a length of insulated conductor that is wound into loops (i.e., “racetracks”) that are subsequently spread apart to form the desired conductor shape. An example of such a process for forming the conductor coils is disclosed in co-pending U.S. patent application Ser. No. 17/716,144, filed Apr. 8, 2022, the entire contents of which are incorporated by reference herein Alternatively, in at least some embodiments, the in-slot segmentsmay be provided by I-pin conductors and the end turnsand coil leadsthat are printed on the ends of the in-slot segmentsafter the I-pin conductors are inserted into the slotsof the core. An example of such a winding is disclosed in co-pending U.S. patent application Ser. No. 17/716,092, filed Apr. 8, 2022, the entire contents of which are incorporated by reference herein.

With continued reference to, each coilincludes two coil leads. Each coil leadprovides a path into or out of the looping portions of each coil. In other words, if the coil body is considered to include the in-slot segmentsand the end turnsthat form loops, the coil leadsprovide a path leading to the coil body.also shows the coils leadin a “bent” or “angled” configuration because a portion of the coil leadfollows the angle of the end turn prior to extending away from the coil body in the radial direction near the vertexof the end turn. However, in the embodiments disclosed herein some of the coilsmay include a “straight” coil lead that extends in an axial direction instead of a radial direction or extends directly from the in-slot segmentsand is not significantly angled like the segments,of the end turn.

As will be recognized from the foregoing, the coil ofis a diamond-shaped coilthat includes a strand of wire that is wrapped in a loop to include a set of left legs, a set of right legs, first end turns, and second end turns. The set of four left legsare all elongated in an axial direction and parallel to one another. Similarly, the set of four right legsthat are all elongated in an axial direction and parallel to one another (and also parallel to the left legs). The first end turnsconnect the right legs to the left legs at one end of the coil, and the second end turnsconnect the right legs to the left legs at the opposite end of the coil. The legs are all connected in series such that a coil is formed, allowing electricity to flow from a first leadat one end of the coil, through all of the legs, and to a second leadat the same axial end of the coil.

Parallel Paths With Pairs of Adjacent Coils

The winding arrangementof the stator includes a plurality of diamond shaped coils similar to that ofconnected together to form a multi-phase winding having multiple parallel paths per phase.shows a representative parallel path for one phase of the winding arrangement. The path includes a first pair of adjacent coilsand second pair of adjacent coilsconnected in series by an extended coil connection(which may also be referred to herein as a “connection segment”). The first pair of adjacent coilsincludes a left coiland a right coil, with the left coilpositioned in slots that are adjacent to the right coil. The second pair of adjacent coils also includes a left coiland a right coil, with the left coilpositioned in slots that are adjacent to the right coil. The term “adjacent coils” as used herein refers to two coils (e.g.,and) having their left legs (e.g., legs) arranged in adjacent slotsof the coreand right legs (e.g., legs) also arranged in adjacent slotsof the core. The first pair of adjacent coilsare not adjacent to the second pair of adjacent coilsbecause none of the legs of the coils of the first pair of adjacent coilsare in adjacent slots on the core to those of the legs of the coils of the second pair of adjacent coils. As shown in, the coiland the coilof the adjacent coilsare connected in series by a weld of leadto lead, as shown in. In another embodiment, the coiland the coilcan be formed of one continuous wire. The coiland the coilare housed in the same stator pole. The two coilsandof adjacent coilsare connected in a similar manner.

The representative path shown inis comprised of two sets of adjacent coilsand, and includes in-slot conductors,, end turn segments, coil leads, connection segments, and path leads. As discussed above, the in-slot conductors,extend through the slots of the stator coreand the end turn segmentsconnect the legs of a given coil which are arranged in different slots. The coil leadsprovide entry and exit nodes between coils and are thus used to connect different coils. Most of the coil leadsinclude a radial segment that extends radially outward from the end turnsand facilitates convenient welding or other connection of the coil leads radially outward from the end turns. However, as noted previously, some of the coil leads may be configured without a radial component. Also, in at least one alternative embodiment, all or most of the coil leads extend axially past the end turns are connection between the end turns is made at an axial end of the stator.

The connection segmentsprovide series connections between coils that are not adjacent (i.e., coils that are not located in adjacent slots of the core). Each connection segmentextends between two different coils and provides a series connection between a first pair of adjacent coils and a second pair of adjacent coils. The connection segmentis shown as a leadof adjacent coilsbent circumferentially toward the leadof adjacent coilsand the two leadsandare welded together. In another embodiment, the connection segmentis a separate jumper wire with one end welded to leadof adjacent coilsto leadof adjacent coils. In the embodiment disclosed herein, the connection segmentsextend in a circumferential manner between the coils at a position that is radially outward from the end turns. Similar to the coils, the connection segmentsare also comprised of insulated copper or another electrically conductive material that is typical in winding arrangements for electric machines.

As noted above, the plurality of path leadsare provided on the lead endof the stator core along with the end turns, the coil leads, and the coil connections. The path leadsdefine the entry and exit conductors into each parallel path of the stator. While all of the path leads are difficult to identify in,shows a representative parallel path of the winding arrangementin isolation and clearly identifies two path leadsandfor the representative path. As discussed previously, each parallel path of the winding arrangementis provided by two pairs of adjacent coils, including a first pair of series-connected adjacent coilsconnected in series to a second pair of series-connected adjacent coilsby a coil connection. Two path leadsandare provided for the parallel path as shown in. The path leadmay be considered the entry path lead (which may also be referred to herein as an “entry lead”), and path leadmay be considered the exit path lead (which may also be referred to herein as an “exit lead”) (or vice-versa). In various embodiments, the path leads may be radially extending or axially extending from the lead endof the stator. For example, the exit path leadis shown as extending radially outward from the end turnsin. The entry path leadextends in the axial and radial directions. Because the statoris a three phase machine, and because there are four parallel paths per phase in the embodiment of, a total of twenty-four path leadsare included in the winding arrangement (i.e., 3 phases×4 paths per phase=12 paths, the twelve paths including twelve entry path leads and twelve exit path leads summing to twenty-four total path leads). For a wye connected stator, twelve of the path leadsare neutral leads and twelve of the path leadsare phase leads.

Complete Winding Arrangement

The plurality of winding paths(such as that shown in) are connected together to form the complete winding arrangement. In the embodiments disclosed herein, the winding arrangementincludes three phase windings (e.g., phase U windings, phase V windings, and phase W windings) with multiple parallel paths for each phase. In each of, the different phases of the winding arrangement are represented by different colors for the sake of clarity and showing the distribution of the various phases throughout the slotsof the stator core. For example, the phase U windings are shown in as a teal color, the phase V windings are shown as a magenta color, and the phase W windings are shown as a seafoam green color. The three phase windings may be star/wye (“Y”) or delta (“Δ”) connected, depending on the desired winding configuration.

shows a view of the winding arrangementpositioned on the lead endof the stator core. In particular,shows a first winding headon the lead endincluding the end turnsof multiple coils, and various connections between the coils. As explained in further detail below, the connections between the coils include leadsto each individual coil, leadsto adjacent coils (seewhich specifically shows path leadsand), and extended coil connectionsthat extend between pairs of adjacent coils. It will be noted that the path leadsare a special type of coil lead(i.e., all path leadsare coil leads, but not all coil leadsare path leadsbecause many coil leadsconnect coils within a path).

shows a second winding headprovided on the opposite end of the stator core from the first winding head. As can be seen in, the winding headonly includes end turns, and does not include, coil leads, connection segments, or leads. Togethershow the opposite ends,of the statorwith the winding heads,of the winding arrangementpositioned on the stator core. The in-slot segmentsof the coilsextend through the slotsbetween the respective winding headsand.

With reference now toa schematic/tabular view of the winding arrangementis shown with the legs of the diamond-shaped coils arranged in the slots of the stator core. As shown in, forty-eight slots (i.e., slot #1 through slot #48) are included on the core, and each slot includes eight layers of conductors (i.e., eight in-slot segmentsextend axially through each slot arranged in a single-file in each slot). As noted on the left side of, these eight layers include “Layer 1” (near the outer diameter “OD” of the core) through “Layer 8” (closer to the inner diameter “ID” of the core). For simplicity, only one phase of conductors is shown in, and the core and associated stator slots are represented in a linear manner (i.e., not in the actual annular form).

Each phase of the winding arrangementincludes four parallel paths of conductors that form coilsas they loop around the slotsand the path winds around the core. Each color inrepresents conductors for one of the four parallel paths for one phase of the winding arrangement. Specifically, these four parallel paths are represented inas a blue path, a green path, a yellow path, and an orange path. The numerals 1-16 are overlaid on each the color of each path,,,. The odd numerals (i.e., 1, 3, 5, etc.) within the color represent in-slot conductors associated with a left leg of a diamond-shaped coil, and the even numerals within the color (i.e., 2, 4, 6, etc.) represent in-slot conductors associated with a right leg of the same diamond-shaped coil. The end turnsthat connect the left and right legs of the coils are not represented in, but it will be recognized that the end turnsjoin the in-slot conductors in sequential order to form the coils (e.g., an end turn at the crown endconnects conductor 1 to conductor 2, an end turn at the lead endconnects conductor 2 to conductor 3, an end turn at the crown end connects conductor 3 to conductor 4, etc.). It will be appreciated fromthat all of the coilshave a pitch of five (i.e., the left legs of each coil are separated from the right legs by five slots). The coilsare also interleaved on the corewith left legs (i.e., in-slot segments) of each coil positioned in the outer half of the slot layers (i.e., layers 1-4), and right legs of the same coil positioned in the inner half of the slot layers (i.e., layers 5-8).

With the above description in consideration, a path of the winding may be traced using the table of. In order to trace a path (e.g., one of,,or), a leadfor the path is first identified by a black box around the conductor numeral “1.” For example, the yellow pathhas a leadin layer #1 of slot 9. From here, a first coil is wound through slot #9 and slot #14 as represented by the sequential conductor numerals 1-8 in those slots (i.e., numerals 1, 2, 3, 4, 5, 6, 7 and 8). A second coil for the yellow path is wound through slot #10 and #15 as represented by the sequential conductor numerals 9-16 (i.e., numerals 9, 10, 11, 12, 13, 14, 15 and 16). The first coil and the second coil are connected in series to form a first pair of adjacent coils for the path. The series connection between the first coil and the second coil is provided by a short jumper connection designated by the blue arrowin, which connects conductor numeral “8” to conductor numeral “9.”

As noted above, the blue arrowsleaning from right-to-left inextend between conductors of a single pair of adjacent coils (i.e., from numeral 8 to numeral 9 of a given path). Accordingly, the blue arrowsrepresent coil leadsthat are connected together to form a pair of adjacent coils. In order to form the short jumper connection (represented by arrow) for the first pair of adjacent coils of the yellow path, short radially-extending coil leads are provided from the ends of conductors extending from conductor numeral “8” in slot #14 and from conductor numeral “9” in slot #10. It will be recognized that the conductor extending from numeral “8” of slot #14 exits the slot and extends leftward, and the conductor extending from numeral “9” of slot #10 exits the slot and extends rightward. The ends of these two conductors are then positioned at a same general circumferential position on the stator core (e.g., somewhere axially outward from slot #12). At this position, the ends of the conductors are directed radially outward from the end turnsand result in coil leads(or jumpers) that are axially and radially aligned. This allows for the coil leads to be easily connected by a weld or other connection that is radially outward from the end turns. While the coil leadsare illustrated herein by short jumpers that are connected together at positions radially outward from the end turns, the coils leadsthat provide the series connection between adjacent coils may alternatively be provided by lengths of continuous wire that simply extend between the appropriate slots (e.g., between conductor numeral “8” in slot #14 and conductor numeral “9” in slot #10). By using lengths of continuous wire to connect the first pair of adjacent coils in series, the need for the short series weld between the coil leadsis eliminated.

After a first pair of adjacent coils is formed for a path, an extended coil connectionconnects the first pair of adjacent coils to a second pair of adjacent coils. For the yellow pathof, the second pair of adjacent coils is illustrated by a third coil for the yellow path wound through slot #21 and slot #26 as represented by the sequential conductor numerals 1-8 in those slots (i.e., numerals 1, 2, 3, 4, 5, 6, 7 and 8), and a fourth second coil for the yellow path wound through slot #22 and #27 as represented by the sequential conductor numerals 9-16 (i.e., numerals 9, 10, 11, 12, 13, 14, 15 and 16). This second pair of adjacent coils is essentially identical in form to the first pair of adjacent coils but is arranged in different slots of the winding arrangement. Accordingly, it will be recognized that the each set of conductor numerals 1-16 inrepresents a pair of adjacent coils that are connected in series within a given path. The first/leftmost group of numerals 1-16 represent the conductors for a first pair of adjacent coils within the path, and the second/rightmost group of numerals 1-16 represent the conductors for a second pair of adjacent coils within the path (i.e., each of the blue path, the green path, the yellow path, and the red pathincludes a first pair of adjacent coils and a second pair of adjacent coils).

As noted above, the extended coil connectionsprovide a series connection between the first pair of adjacent coils and the second pair of adjacent coils within each path. These extended coil connections are illustrated inby the red arrowsleaning from left-to-right and extending between the leads of pairs of adjacent coils (i.e., from numeral 16 to numeral 1 of a given path). In order to provide the extended coil connectionsthe end of the conductor numeral 16 for the first pair of adjacent coils of a given path is extended radially outward to provide a coil lead. For example, for the yellow path, the conductor numeral “16” in layer 5 of slot #15 is bent leftward and then radially outward past the end turnsto provide a coil leadin the vicinity of slot #13. From this position radially outward from the end turnsa jumper connects the end of conductor numeral “16” extending from layer 5 of from slot #15 to the end of conductor numeral “1” extending from layer 1 of slot #21. The jumper that provides the extended coil connectionmay be easily connected to the coil lead by a weld or other connection that is radially outward from the end turns, closer to the outer diameter of the stator core. A view of an exemplary coil connectionin isolation from the stator coreand other paths of the windingis shown in. As shown in the figure, the jumper that provides the extended coil connectionextends along an arc that radially outward from the end turns of the first pair of adjacent coilsand the second pair of adjacent coils. The arc extends along a circumferential length that is less than 90°. The jumper further includes a left side terminal end that is axially and radially aligned with the coil leadthat extends radially outward from one of the inner layers of conductors. While the extended coil connectionsare described in the embodiments herein by extended jumpers that are connected together at positions radially outward from the end turns, the extended coil connections that provide the series connection between a first pair of adjacent coils and a second pair of adjacent coils within a path may alternatively be provided by lengths of continuous wire that simply extend between the appropriate slots, similar to the manner described herein, but without the need for welds between the coil leads.

The description above discloses the pattern for the yellow pathof phase U of the winding arrangement in some detail. It will be recognized that this same pattern is repeated for the blue path, the green path, and the orange pathof phase U in different slots of. Each of those additional paths,andis not described in detail herein for the sake of brevity. The phase V and phase W paths are also similar to the phase U paths, with the phase V conductors housed in the light gray slots of, and the phase W conductors housed in the dark gray slots of. Again, the phase V and phase W paths are not described in detail herein for the sake of brevity.

Features of the Winding Arrangement

With continued reference to, additional features of the winding arrangement can be appreciated other than the simple path of the conductors through the slots. For example, it can be seen fromthat each phase of the winding arrangementis associated with eight poles(labeled 1-8 above the slot numbers in). Additionally, each polewithin a phase of the winding arrangementis associated with a pole slot set. In the embodiment of, each pole slot setincludes three contiguous slots, and each slot houses eight layers of conductors. Each pole slot setalso defines a 4-8-4 conductor arrangement such that four conductors of a first parallel path are arranged in inner layers (i.e., layers 5-8) of the leftmost slot, four conductors of the first parallel path are arranged in inner layers of the middle slot, four conductors of a second parallel path are arranged in outer layers (i.e., layers 1-4) of the middle slot, and four conductors of the second parallel path are arranged in outer layers of the rightmost slot.

Another feature of the winding ofis the number of slots per pole per phase (SPPPP) is equal to two. SPPPP is simply the number of conductors of one phase in one pole divided by the number of conductors per slot (CPS). Ineach pole of each phase houses sixteen conductors (e.g., in the pole associated with slot #s 21-23, there are four conductors in slot #20, eight conductors in slot #21 and four conductors in slot #22), and the number of CPS is equal to eight (e.g., 8 conductors in slot #21). Therefore SPPPP=16/8=2.

Furthermore, another feature of the winding arrangement is rotation degree of each parallel path (i.e., the degree of an arc spanned by each parallel path) as well as the placement of the leads of each parallel path. Each parallel path does not span an arc of 360 degrees and stops from completing a complete 360 degrees rotation by at least two poles. For example, in, the stator has eight polesbut the yellow parallel path has an entry lead in pole #2 (i.e., the lead identified as conductor numeral “1” in slot 9) and an exit lead in pole #5 (i.e., the lead identified as conductor numeral “16” in slot 27). Therefore, as can be seen from, the yellow parallel path is not associated with at least two poles, and to be exact—is not associated with 4 poles—because pole #6, pole #7, pole #8 and pole #1 are not associated with the yellow parallel path between the leadof the parallel path to the leadof the parallel path. Consequently, the leads of all the parallel paths are dispersed around a large arc of the stator. For the example of, entry leadsexist in pole #2 (i.e., the yellow path entry lead identified by conductor numeral “1” in slot 9), pole #3 (i.e., the blue path entry lead identified by conductor numeral “1” in slot 15), pole #6 (i.e., the green path entry lead identified by conductor numeral “1” in slot 33), and pole #7 (i.e., the orange path entry lead identified by conductor numeral “1” in slot 39), while exit leadsexist in pole #1 (i.e., the green path exit lead identified by conductor numeral “16” in slot 3), pole #2 (i.e., the orange path exit lead identified by conductor numeral “16” in slot 9), pole #5 (i.e., the yellow path exit lead identified by conductor numeral “16” in slot 27), and pole #6 (i.e., the blue path exit lead identified by conductor numeral “16” in slot 33). Therefore, the leadsandextend between pole #1 to pole #7, and since eight poles exist in the stator, all the leadsandare arranged in an arc that spans essentially 315 degrees (i.e., 7 divided by 8×360°=315°), or in at least some embodiments, an arc that spans at least a 240 degrees around the core.

Yet another feature of the winding arrangement is each parallel path includes a first pair of adjacent coilsthat fills the outer half of layers of X poleand the inner half of layers of X+1 pole, and a second pair of adjacent coilsthat fills the outer half of layers of Y poleand the inner half of layers of Y+1 pole, where Y does not equal X+1. For example, as shown in, a first pair of adjacent coils for the yellow path fills the outer half of pole #2 (i.e., “X pole”) and the inner half of layers of pole #3 (i.e., the “X+1” pole), and a second pair of adjacent coils for the yellow path fills the outer half of pole #4 (i.e., the “Y pole”) and the inner half of layers of pole #5 (i.e., the “Y+1 pole”).

It will be recognized fromthat, for each pole slot set, two parallel paths of one phase travel through the slots of the pole slot set. For example, pole #3 is associated with pole slot set, which includes slot #s 14, 15 and 16. In this pole slot set, the yellow pathis retained in the inner layers of the leftmost slot (i.e., layers 5-8 of slot #14), the yellow pathis retained in the inner layers of the middle slot (i.e., layers 5-8 of slot #15), the blue pathis retained in the outer layers of the middle slot (i.e., layers 1-4 of slot #15), and the blue pathis retained in the outer layers of the rightmost slot (i.e., layers 1-4 of slot #16). In this pole slot set, it will be recognized that the yellow path conductors in layers 5-8 of slot #14 (i.e., the inner layers of the leftmost slot) are associated with a first coil of a first pair of adjacent coils, and the yellow path conductors in layers 5-8 of slot #15 (i.e., the inner layers of the middle slot) are associated with a second coil of the first pair of adjacent coils.

It will be further appreciated fromthat the positions of the various paths travel through different slots and different layers of said slots depending on the particular pole slot set. For example, the blue pathis (i) retained in the inner layers of the leftmost and middle slots in the pole slot sets associated with poles #4 and #6, and (ii) retained in the outer layers of the middle and rightmost slots in the poles slot sets associated with poles #3 and #5. As another example, the yellow pathis (i) retained in the inner layers of the leftmost and middle slots in the pole slot sets associated with poles #3 and #5, and (ii) retained in the outer layers of the middle and rightmost slots in the pole slot sets associated with poles #2 and #4. The other paths, including the green pathand orange pathalso travel through their associated pole slot sets in a similar manner (i.e., arranged in the left, middle, and/or right slots of different pole slot sets and in different layers of the associated slots).

Again, whilespecifically shows the parallel paths,,,through the pole slot setsfor one phase of the winding arrangement, the pole slot sets for two additional phases of the winding arrangement are also represented inby the gray shading and white shading (but no numerals). The term “adjacent pole slot sets” as used herein refers to two pole slot sets associated with consecutive/adjacent poles. For example, consecutive poles #5 and #6 indefine adjacent pole slot sets (i.e., the pole slot setsshown in association with pole #5 and pole #6). In the embodiments described herein, the conductors forming each coils are also located in adjacent pole slot sets. However, in at least some embodiments, the conductors forming coils may could be extended such that they are not be located in adjacent pole slot sets.

also illustrates the extended coil connectionsthat provide series connections between the pairs of adjacent coils,of the winding arrangement. These coil connectionsare disclosed herein as jumpers that are arranged radially outward from the end turnsand extend circumferentially around the end turns (e.g., as shown in). These coil connectionsare represented inby red arrowsand have a pitch of six. Each red arrowrepresents a coil connectionthat connects two different pairs of adjacent coils within a parallel path via a series connection between coil leads extending from layer #5 of one pole and coil leads extending from layer #1 of a different pole. In other words, the red arrowsrepresent coil connectionsthat connect a first coil lead associated with a first pair of adjacent coils coil (which first coil lead extends from a right leg of the first coil and is positioned in an inner layer of a slot—and particularly layer #5) to a second coil lead of a second coil associated with a second pair of adjacent coils (which second coil lead extends from a left leg of the second coil positioned in an outer layer of another slot—and particularly layer #1).

In addition to all of the foregoing, it will also be recognized thatfurther illustrates the position of the leadsfor each pair of adjacent coils of the winding arrangement. As noted previously, the leadsare represented inby black boxes around the associated conductors and a slightly darker fill color. The leadsinclude outer layer leads(i.e., leads in layer 1 identified by black boxes around the conductor numeral “1”) as well as inner layer leads(i.e., leads in layer 5 identified by black boxes around the conductor numeral “16”). A total of sixteen different leadsare shown for the winding arrangement, including the outer layer leadsshown by the eight black boxes around the “1” conductors in layer #1 of each poles, and the inner layer leadsshown by the eight black boxes around the “16” conductors in layer 5 of each pole.

further illustrates the leads for each parallel path of the winding arrangement. In particular, the leadsinthat do not have an arrow associated with the box (i.e., neither blue arrownor red arrowextends from or to the associated box) are path leads. For example, leadsinare entrance leads to a path, and leadsare exit leads to a path. It will be recognized that each of the leadsandshown inare either phase leads or neutral leads for the winding arrangement. The leadsthat are part of the outer layer leads(i.e., extending from layer #1) alternate between neutral leads and phase leads. For example, if the path leadof pole #2 is a phase lead (i.e., the yellow path lead identified by conductor numeral “1” of slot #9), then the leadof pole #3 is a neutral lead (i.e., the blue path lead identified by conductor numeral “1” of slot #15), the leadof pole #6 is a phase lead (i.e., the green path lead identified by conductor numeral “1” of slot #33), and the leadof pole #7 is a neutral lead (i.e., the orange path lead identified by conductor numeral “1” of slot #45). The path leadsthat are inner layer leads(i.e., extending from layer #5) also alternate between neutral leads and phase leads, but are different from the outer layer leadswithin each path (i.e., the path leadsthat are inner path leadsare either phase leads or neutral leads, whatever is different from the outer layer leads for the same path). For example, if (as noted above) the path-in leadof pole #2 is a phase lead (i.e., the yellow path lead identified by conductor numeral “1” of slot #9), then the path-out leadof pole #5 is a neutral lead (i.e., the yellow path lead identified by conductor numeral “16” of slot #27).

shows a perspective view of the complete winding arrangementin isolation from the corein order to illustrate the relative positions and interconnections between the coils. As shown in, each phase of the winding includes eight pairs of adjacent coils. Each parallel path in each phase of the windingis provided by a first pair of adjacent coils connected in series to a second pair of adjacent coils. Accordingly, each phase of the winding includes four parallel paths, each parallel path comprised of two pairs of adjacent coils connected in series by the extended coil connections. The coil connectionsextend circumferentially between the pairs of adjacent coils along the outer diameter (OD).

While the statorand winding arrangementhave been described herein with particular detail for the embodiment of, it will be recognized that alternative embodiments of the winding arrangementare contemplated.shows one such alternative embodiment. The embodiment ofis similar to that of, but in the embodiment of, the first pair of adjacent coilsis separated from the second set of adjacent coilsto a greater degree. In particular, the first pair of adjacent coilsis separated from the second pair of adjacent coilsby about 180°. Accordingly, the jumper that provides the extended coil connectionin this embodiment extends along an arc that is greater than 90° but less than 180° (e.g., an arc of about 120° to 150°). Further, for any given parallel path, the number of poles between the path input leadand the path output leadwhich are not associated with said parallel path, equals two. For example, for the blue path in, the first pair of adjacent coilsis associated with pole #3 and pole #4, and the second pair of adjacent coilsis associated with pole #7 and pole #8. However, the blue path is not associated with pole #5 or pole #6. Thus, two poles (i.e., pole #5 and pole #6) exist between the input path leadfor the blue path (see numeral “1” in slot #15) and the exit path lead (see numeral “16” in slot #45), with pole #3, pole #4, pole #7 and pole #8 all being associated with the blue path, but pole #5 and pole #6 not associated with the blue path. The embodiment ofhas the advantage that the winding arrangement prevents recirculating currents in the event the rotor (not shown) of the electric machine is not precisely centered within the stator.

shows another alternative embodiment of the statorand winding arrangement. In this embodiment, the winding arrangementis configured for an electric machine with a greater number of slots per pole per phase. In the exemplary embodiment of, the winding is a three-phase winding with three parallel paths per phase (represented by a blue path, a green path, and an orange path) and four slots per pole per phase. Instead of a first pair and a second pair of adjacent coils connected in series like the embodiments of, the winding ofincludes a first set of four adjacent coils connected in series (i.e., multiple pairs of adjacent coils connected in series) and a second set of four adjacent coils connected in series. In this embodiment, the first set of adjacent coils is connected in series to the second set of coils with the first set of adjacent coils being separated from the second set of adjacent coils by about 180°. Also, it will be recognized that the embodiment ofincludes six layers of conductors arranged in each slot, and each pole slot set defines a 3-6-6-6-3 conductor arrangement. With this arrangement (i) three conductors of a first parallel path are arranged in inner layers of each of the leftmost slot, a left intermediate slot, the middle slot, and a right intermediate slot, and (ii) three conductors of a second parallel path are arranged in outer layers of each of the left intermediate slot, the middle slot, the right intermediate slot, and the rightmost slot.

Although the various embodiments have been provided herein, it will be appreciated by those of skill in the art that other implementations and adaptations are possible. Furthermore, aspects of the various embodiments described herein may be combined or substituted with aspects from other features to arrive at different embodiments from those described herein. Thus, it will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by any eventually appended claims.